Soybeans:Diagnostics

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SOYBEAN PESTS AND NUTRITIONAL DISORDERS



Contents

ALTERNARIA LEAF SPOT AND POD NECROSIS (ALTERNARIA SPP)

‘‘‘Alternaria Leaf Spot and Pod Necrosis (Alternaria spp.) ‘‘‘ Brown, dry leaf spots with concentric rings appear on infected foliage, enlarge, and may group together to form larger dry areas. Infected leaves eventually dry out and drop prematurely. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


ALTERNARIA POD AND SEED DECAY (ALTERNARIA TENUISSIRNA)

‘‘‘Alternaria Pod and Seed Decay (Alternaria tenuissirna) ‘‘‘ Condia are smooth and pale brown to golden, with short or long beaks with an occasional terminal beak swelling. They are formed in short, unbranching chains of eight or fewer. Control of disease is obtained by controlling insects and avoiding pod injury. (Seedborne Fungi and Fungal Disease)


AMMONIA

‘‘‘Ammonia: ‘‘‘ Leaves that are almost fully expanded are most sensitive to ammonia. The injury ranges from local, reddish brown lesions to broad, cream to brown bands between veins. The pollutant source must be known in order to distinguish ammonia damage from that caused by other pollutants. (Air Pollutants)


ANTHRACNOSE (COLLETOTRICHUM TRUNCATUM)

‘‘‘Anthracnose (Colletotrichum truncatum) ‘‘‘ Symptoms typically appear in the early reproductive stages on stems, pods, and petioles as irregularly shaped brown areas and may resemble pod and stem blight. Stems, pods, and leaves may be infected without showing symptoms. In advanced stages of anthracnose, usually in the late reproductive stages, infected tissues are covered with black fruiting bodies, which produce small black spines that can be seen with the unaided eye. The best control measures are using a recommended fungicide, plowing under crop residues, and rotating soybeans with other crops. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


BACILLUS SEED DECAY (BACILLUS SUBTILIS)

‘‘‘Bacillus Seed Decay (Bacillus subtilis) ‘‘‘ The bacterium causes a soft decay of seeds which increases with moisture and higher temperatures. The bacterium produces rough or smooth, slimy, glistening colonies on soybean seeds. Use mulch at planting time and antibiotic seed treatment for prevention. (Seedborne Bacteria and Bacterial Diseases of Seeds)


BACTERIAL BLIGHT (PSEUDOMONAS SYRINGAE PV GLYCINEA)

‘‘‘Bacterial Blight (Pseudomonas syringae pv glycinea) ‘‘‘ Bacterial blight lesions are most conspicuous on leaves but also occur on stems, petioles, and pods. Small, angular, translucent, water-soaked, yellow to light brown spots appear on leaves. Commonly, lesions first appear on cotyledons, usually at the margins. The lesions enlarge and turn dark brown as the tissue collapses. Pod lesions, small and water-soaked, later enlarge and merge to involve much of the pod. They turn dark brown to black with age. The best form of control is proper cultural practices. (Bacterial Disease)


BACTERIAL PUSTULE (XANTHOMONAS CAMPESTRIS PV GLYCINES)

‘‘‘Bacterial Pustule (Xanthomonas campestris pv glycines) ‘‘‘ Early symptoms are small, pale green spots with elevated centers on either or both leaf surfaces. Later, a small, raised, light-colored pustule forms in the center, usually in lesions on the under leaf surface. Leaves become ragged when dead areas are torn away by wind. Severe infection often results in some defoliation. Follow the control measures suggested for bacterial blight and use resistant cultivars. (Bacterial Disease)


BACTERIAL TAN SPOT (CURTOBACTERIUM FLACCUMFACIENS PV FLACCUMFACIENES)

‘‘‘Bacterial Tan Spot (Curtobacterium flaccumfaciens pv flaccumfacienes) ‘‘‘ Infection begins with a small lesion, which enlarges until the entire leaflet is involved. Yellowing begins in oval or elongated patterns, frequently along leaf margins, and progresses inward toward the midrib. Infected tissues die, dry out, and turn brown. Use resistant cultivars and plant uninfected seeds. (Bacterial Disease)


BACTERIAL WILTS (CURTOBACTERIUM FLACCUMFACIENS PV FLACCUMFACIENES)

‘‘‘Bacterial Wilts (Curtobacterium flaccumfaciens pv flaccumfacienes) ‘‘‘ Bacterial wilts cause a progressive wilt with leaf yellowing and vascular discoloration. Leaves die, dry out, and remain on the plant. Infected plants are weak and stunted and eventually die. Use sanitation practices and follow the control practices suggested for bacterial blight. (Bacterial Disease)


BEAN POD MOTTLE VIRUS (BPMV)

‘‘‘Bean Pod Mottle Virus (BPMV) ‘‘‘ Young leaves in the upper canopy exhibit green to yellow spotting. Symptoms are masked during periods of high temperatures and are not observed on plants after pod set. Grow at least four rows of maize, forage sorghum, or other tall-growing crops between soybeans and other leguminous crops. Apply a herbicide to kill broadleaf weeds in noncrop areas next to soybean fields. (Virus Disease)


BEAN YELLOW MOSAIC VIRUS (BYMV)

‘‘‘Bean Yellow Mosaic Virus (BYMV) ‘‘‘ A conspicuous yellow spotting of the leaves is characteristic. The yellow areas are either scattered or produced in indefinite bands along the major veins. Rusty, dry spots appear in the yellow areas as the leaves mature. Some strains produce severe spotting and crinkling of leaves. (Virus Disease)


BLACK GRAM MOTTLE VIRUS (BGMV)

‘‘‘Black Gram Mottle Virus (BGMV) </b></S></CF> Black gram mottle virus (BGMV) causes a mild mottle disease of soybeans and is mechanically transmissible and has isometric particles about 28 nm in diameter. The virus can infect plants in at least six families. Susceptible soybean genotypes react with a systemic mild mottle, and resistant ones with necrotic local lesions.


BORON DEFICIENCY

‘‘‘Boron Deficiency ‘‘‘ Boron deficiency is not common in soybeans but may occur in sandy, leached soils, low organic matter soils, alkaline soils or very acid soils. Drought accentuates deficiency. Symptoms of the deficiency include shortened internodes and yellowing or reddening of upper leaves. Flowers fail to develop, particularly in dry weather. Boron deficiency may be confused with leaf-hopper injury and potassium or calcium deficiency. Excessive boron, especially near rows and in sandy soils, is extremely toxic to soybeans, especially seedlings. Affected plants are stunted. Toxicity symptoms appear only on leaves, usually those that are just opening. The pubescence at the leaf tip becomes brown. This symptom is followed by browning of the leaf tip and progressive browning of the entire leaf. Boron deficiency is best prevented by broadcasting soluble boron salts such as sodium borate. Care should be taken to avoid over-application. The window between deficiency and toxicity is narrow. (Mineral Deficiencies and Toxicities)


BROWN SPOT (SEPTORIA GLYCINES)

‘‘‘Brown Spot (Septoria glycines) ‘‘‘ Irregular dark brown spots varying from minute specks appear on both upper and lower surfaces of unifoliolate leaves. These leaves quickly turn yellow and drop. Adjacent lesions frequently group together to from irregularly shaped blotches. Numerous irregular, light brown lesions form on trifoliate leaves. These lesions gradually darken until they become chocolate brown to blackish brown. Plow under susceptible cultivars and apply a foliar fungicide from bloom to pod fill. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


BROWN STEM ROT (PHIALOPHORA GREGATA)

‘‘‘Brown Stem Rot (Phialophora gregata) ‘‘‘ Infection becomes apparent about mid-season. A dark reddish brown discoloration of the vascular elements and pith occurs extending up from the roots or crown of the plant. External symptoms may appear late in the growing season. The lower part of infected stems turns dull brown and this symptom is followed by sudden blighting and drying of leaves, which may drop prematurely. Tissues between the veins turn brown, and a narrow green border may outline the veins for a few days. Rotate soybeans and use resistant cultivars. (Fungal Disease of Roots and Lower Stems)


CALCIUM DEFICIENCY

‘‘‘Calcium Deficiency ‘‘‘ Calcium deficiency is not common in soybeans but is most likely in acid, sandy soils. Adequate calcium is necessary for normal nitrogen fixation. Deficiency symptoms include delayed development of primary leaves, wilting or death of growing points, and yellowing of young leaves. Pods may be soft and seeds may fail to develop. Calcium deficiency may also cause poor nodulation, symptoms of nitrogen deficiency, and increased damping off. Calcium is a key component of cell walls and membranes. Deficiency is prevented by liming or application of soluble calcium salts such as gypsum.


CERCOSPORA BLIGHT AND LEAF SPOT (CERCOSPORA KIKUCHII)

‘‘‘Cercospora Blight and Leaf Spot (Cercospora kikuchii) ‘‘‘ The first symptoms of the disease are observed at the beginning of and throughout seed set. Upper leaves exposed to the sun have a light purple appearance. Reddish purple, angular to irregular lesions later occur on both the upper and the lower surfaces of leaves. A general dark reddish purple discoloration, similar to that of upper leaves, also occurs on upper stems, petioles, and pods exposed to the sun. Infection may be latent, with no symptoms expressed. Use resistant cultivars. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


CERCOSPORA SOJINA (CERCOSPORA SOJINA)

‘‘‘Cercospora sojina (Cercospora sojina) ‘‘‘ Infected seeds develop conspicuous light to dark gray or brown areas, which vary from specks to large blotches covering the entire seed coat. The greater the area of discoloration, the greater the delay of germination. Some lesions show alternating bands of light and dark brown. (Seedborne Fungi and Fungal Disease)


CHAETOMIUM CUPREUM

‘‘‘Chaetomium cupreum: ‘‘‘ Cupreum produces a compound that inhibits seed germinaiton and the growth of other fungi associated with soybean seeds. It also produces a copper-colored pigment on agar, which can be confused with that produced by Cercospora kikuchii. (Seedborne Fungi and Fungal Disease)


CHARCOAL ROT (MACROPHOMINA PHASEOLINA)

‘‘‘Charcoal Rot (Macrophomina phaseolina) ‘‘‘ Infected plants at first produce leaves smaller than normal and show a subtle loss of vigor. In a more advanced stage, leaves turn yellow and wilt but remain attached. Rotate, fertilize, and irrigate soybeans. (Fungal Disease of Roots and Lower Stems)


CHOANEPHORA LEAF BLIGHT (CHOANEPHORA INFUNDIBULIFERA)

‘‘‘Choanephora Leaf Blight (Choanephora infundibulifera) ‘‘‘ Symptoms occur in the field after two or three consecutive days of rain when the weather is cool and the relative humidity is close to saturation. The first symptom of the disease appears on mature leaves and occasionally on young leaves at the top of the plant. Infected areas of leaves first appear grayish, similar to leaves with hot-water scald injury, and then turn dark. Remove and destroy infected plant parts and use resistant cultivars where available. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


COLLETOTRICHUM TRUNCATUM

‘‘‘Colletotrichum truncatum: ‘‘‘ Seeds may show no symptoms or may develop brown staining or small, irregular gray areas with black specks. The fungus is confined at first to the seed coat. Infected seeds may die during germination, or if they do germinate, may produce infected seedlings. (Seedborne Fungi and Fungal Disease)


COPPER DEFICIENCY

‘‘‘Copper: ‘‘‘ Soybeans are not usually deficient in copper. Copper deficiency is most likely to occur in high pH, low organic matter soils, alkaline peat and muck soils, and acid, sandy, highly leached soils. Yield reductions may occur in plants with no obvious symptoms. Usual symptoms are wilting or lack of turgor in new leaves, in some cases resembling calcium deficiency, and chlorotic leaf tips. Deficiency can be detected by soil and plant analysis. Copper deficiency is prevented by application of soluble copper fertilizers, such as copper sulfate or copper EDTA. Fertilizer rates are generally about 0.5 to 1.0 lb Cu/acre. Rates of 2-3 lbs copper/acre may be effective for several years, but these rates should be broadcast not banded. Foliar sprays of copper sulfate or copper EDTA are also effective. (Mineral Deficiencies and Toxicities)


COWPEA CHLOROTIC MOTTLE VIRUS (CCMV)

‘‘‘Cowpea Chlorotic Mottle Virus: ‘‘‘ The predominant symptoms are mosaic and stunting and leaf distortion, yellow patches, and rugosity. The best form of control is the use of resistant cultivars. (Virus Disease)


COWPEA MILD MOTTLE VIRUS (CMMV)

‘‘‘Cowpea Mild Mottle Virus (CMMV) </b></S></CF> Cowpea mild mottle virus (CMMV) is a carla virus with rod-shaped particles 650~700 nm long. It can remain infectious for up to 21 days at 20°C. The virus is mechanically transmitted.


COWPEA SEVERE MOSAIC VIRUS (CSMV)

‘‘‘Cowpea Severe Mosaic Virus (CSMV) </b></S></CF> Cowpea severe mosaic virus (CSMV) causes severe mosaic and stunting. Soybean plants inoculated 14 days after planting often die prematurely. The causal agent belongs to the comovirus group. The virus is primarily restricted to leguminous plants. CSMV can be mechanically transmitted and beetle-transmitted.


CRUSTING AND COMPACTION

‘‘‘Crusting and Compaction: ‘‘‘ When heavy rain falls on fine-textured soil, a hard crust may form and prevent germinated soybean seeds from emerging. The stems of such seedlings become thickened, and in severe cases, the hypocotyl arch is cracked or broken. Rotary hoeing or hand-hoeing to break up the surface crust may aid emergence. (Environmental Stress)


DOWNY MILDEW (PERONOSPORA MANSHURICA)

‘‘‘Downy Mildew (Peronospora manshurica) ‘‘‘ Downy mildew appears on the upper surface of young leaves as pale green to light yellow spots, which enlarge into pale to bright yellow lesions of indefinite size and shape, depending on leaf age. They may later turn grayish brown to dark brown with a yellowish green margin and may finally become entirely brown. Treat with a fungicide and plow under soybean residue. Rotate soybeans and use resistant cultivars when feasible. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


FLUORIDES

‘‘‘Fluorides: ‘‘‘ The most common symptom of fluoride injury to soybeans is marginal yellowing and drying of older leaves. Knowledge of nearby fluoride source and foliar analysis for fluoride content are required for diagnosis. (Air Pollutants)


FOLIAGE BLIGHT

‘‘‘Foliage Blight: ‘‘‘ Symptoms appear first on the lower leaves and advance to the upper ones. Discrete, water-soaked, orange-brown specks form on leaves and later, these enlarge to round or irregularly shaped orange-brown lesions with definite, dark brown margins.


FROGEYE LEAF SPOT (CERCOSPORA SOJINA)

‘‘‘Frogeye Leaf Spot (Cercospora sojina) ‘‘‘ The lesions are circular to angular spots varying in size. When they are first visible on the upper surface of leaves, they are approximately the size of mature lesions. They begin as dark, water-soaked spots, with or without a lighter center, and develop into brown spots surrounded by a narrow, dark reddish brown margin. Young stem lesions are deep red with a narrow, dark brown to black margin and the central area is flattened or slightly sunken. Lesions on pods are circular to elongate, slightly sunken, and reddish brown. Older lesions become brown to light gray, usually with a narrow, dark brown border. The best forms of control include resistant cultivars, treating seeds with a fungicide, and plowing under crop residues. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


FROST

‘‘‘Frost: ‘‘‘ Frost-damaged plants are common in temperate growing areas. Often only the upper part of the plant is killed or damaged, and regrowth soon appears at one of the unaffected nodes. If the new growth is strong and vigorous, and if few plants are damaged severely, replanting may not be needed. (Environmental Stress)


FUSARIUM BLIGHT OR WILT, ROOT ROT, AND POD AND COLLAR ROT (FUSARIUM SPP)

‘‘‘Fusarium Blight or Wilt, Root Rot, and Pod and Collar Rot (Fusarium spp.) ‘‘‘ Fusarium Blight or Wilt: The most characteristic symptom is browning or blackening of the vascular system in roots and stems, which is evident when stems are split open. Leaves of affected plants may become yellow, wither, and eventually drop. Fusarium Root Rot: Infection is generally confined to the roots and lower stem. Cotyledons of diseased seedlings are yellow and later dry up. The lower part of the taproot and lateral root system may be destroyed. Pad and collar rot: Depressed, water-soaked, cream-colored, serrated lesions form on cotyledons and hypocotyls of emerging or slightly older seedlings. As the seedlings mature, these areas turn dark brown to black and eventually group together to form large lesions. Pods may dry prematurely with the drying beginning at the pod tip and progressing toward the base. Pods eventually turn dark brown to black. The use of resistant cultivars is the best form of control. (Fungal Disease of Roots and Lower Stems)


GLIOCLADIUM (GLIOCLADIUM ROSEUM)

‘‘‘Gliocladium (Gliocladium roseum) </b></S></CF> Gliocladium is a soilborne fungus that is common among soybeans. Spores develop which appear a mucilaginous drops, but which fuse to form balls of condia as the colonies age.


HAIL

‘‘‘Hail: ‘‘‘ Leaves injured by hail are torn and ragged and large areas of tissues may be beaten away. Stems may be cut off or broken or may have sunken, dark areas. Pathogenic fungi may colonize hail-damaged areas and produce stem-girdling cankers or weaken the stems. Most damage is usually on the side of the plant facing the prevailing winds of the storm. (Environmental Stress)


HEAT CANKER

‘‘‘Heat Canker: ‘‘‘ Heat canker girdles the hypocotyl at or just above the soil line. The affected area varies in length, with the affected tissues appearing reddish brown and shriveled. Hypocotyl tissue directly above or below the constriction appears normal. (Environmental Stress)


INDONESIAN SOYBEAN DWARF VIRUS (ISDV)

‘‘‘Indonesian Soybean Dwarf Virus (ISDV) ‘‘‘ The virus induces dwarfing, with shortened leaf petioles and internodes, and infected plants are often dark green. Upper leaves are small and often crinkled and curled. Lower leaves show rugosity and are often brittle. (Virus Disease)


IRON DEFICIENCY

‘‘‘Iron Deficiency ‘‘‘ Iron chlorosis, the name given to iron deficiency symptoms, occurs frequently in soybeans grown on high pH soils containing free calcium carbonate. Iron availability declines rapidly as soil pH increases. Water-logging of the soil worsens the symptoms, but the effect may be temporary and disappear as the soil dries. Iron chlorosis typically occurs on the new leaves as a distinctive yellowing of the tissue between veins while the veins remain green. Severely chlorotic leaves may be almost white and have necrotic areas. The best method of prevention is variety selection. So-called iron-efficient cultivars are less susceptible to chlorosis and should be planted if chlorosis has been observed previously and soil conditions are conducive to development of deficiency. Soil applications of iron fertilizers are generally ineffective in correcting iron deficiency. The most effective corrective treatment is foliar sprays of soluble iron materials, such as iron chelates or ferrous sulfate. A 0.5 to 1.0% solution of ferrous sulfate with a surfactant sprayed in enough water to wet the leaves (about 20 gals/acre) is effective. Multiple applications at 7-14 day intervals may be necessary. The only soil treatment shown to be effective is iron EDDHA, a very expensive chelate that is stable at high soil pH. (Mineral Deficiencies and Toxicities)


LANCE NEMATODES (HOPLOLAIMUS COLUMBUS)

‘‘‘Lance Nematodes (Hoplolaimus columbus) ‘‘‘ Yellow, stunted plants result from feeding by Lance nematodes and several tolerant cultivars exist. (Nematode Disease)


LESION NEMATODES (PRATYLENCHUS SPP)

‘‘‘Lesion Nematodes (Pratylenchus spp.) ‘‘‘ Lesion nematodes are endoprarsitic and attack the root cortex. Their feeding generally causes dark lesions and an overall browning of the roots, which may decrease root growth. The epidermis and cortex of severely infected roots may slough away from the stele. Use resistant cultivars as a control for lesion nematodes. (Nematode Disease)


LIGHTNING

‘‘‘Lightning: ‘‘‘ Lightning kills soybeans in circular spots in the field, with a wide border of damaged plants. The lower parts of stems may be blackened, with many dead leaves still attached. The pith of such plants appears cooked or blanched. (Environmental Stress)


MACHISMO

‘‘‘Machismo: ‘‘‘ The first symptoms usually appear about the time of flowering or after pod formation begins. Pods may be rigid, curved, flat, and thin, usually in an upright position, with no beans formed. Flowers are smaller and remain closed. Control measures include controlling weed hosts and roguing infected plants. (Mycoplasmalike Disease)


MAGNESIUM DEFICIENCY

‘‘‘Magnesium Deficiency ‘‘‘ Magnesium deficiency in soybeans occurs most frequently in acid, sandy soils or acid soils limed with calcitic limestone. Magnesium deficiency is recognized by pale green to yellow interveinal tissues on the leaf blade. Leaves later become deep yellow, except at the base. The lowest leaves show symptoms first and as the disease progresses, rusty specks and dry blotches may appear between the veins and around the edges of middle and upper leaves. The deficiency gives older plants the general appearance of early maturity. Leaf margins curve down, with a gradual yellowing from the margin inward, followed by bronzing of the entire leaf. Magnesium deficiency is prevented by liming with dolomitic limestone. On high pH soils, or where dolomite is not available, soluble salts of magnesium are effective. Magnesium sulfate or potassium-magnesium sulfate are commonly used. (Mineral Deficiencies and Toxicities)


MANGANESE DEFICIENCY

‘‘‘Manganese Deficiency ‘‘‘ Manganese deficiency occurs often in soybeans grown on high-pH, sandy, overlimed, poorly drained, or high organic matter soils. Interveinal areas of leaves become light green to white while the veins remain green. The symptoms resemble the early symptoms of iron deficiency, except the veins of manganese deficient leaves remain green and stand out prominently. Dry, brown spots develop as the deficiency becomes more severe and leaves may drop prematurely. Excess soil iron can accentuate the deficiency. Manganese deficiency may be prevented by applications of manganese sulfate. Band applications are recommended. Broadcast applications of manganese on high pH soils are not recommended. Manganese EDTA applications have not been effective and in some cases have actually worsened the deficiency. Insoluble manganese fertilizers such as manganese oxide are not effective. Manganese deficiency detected early in the season may be corrected with foliar sprays of manganese sulfate or manganese EDTA. Multiple applications may be necessary. (Mineral Deficiencies and Toxicities)


MOLYBDENUM DEFICIENCY

‘‘‘Molybdenum Deficiency: ‘‘‘ Molybdenum deficiency is rare on adequately limed soils. Molybdenum deficiency can occur in acidic soils of high iron and aluminum content. Molybdenum availability decreases as pH decreases. The only known functions of molybdenum are in nitrogen fixation and nitrate reduction in the plant. Severe yield reductions may result if the deficiency occurs. Symptoms of deficiency resemble those of nitrogen deficiency and are probably caused indirectly by reduced nitrogen utilization rather than directly by lack of molybdenum. Leaves are pale green or yellow, dry, and twisted. The drying is largely confined to the midribs, interveinal areas, and margins. Molybdenum deficiency is usually prevented by liming acid soils. Because of the extremely small amounts of molybdenum needed by plants, seed treatments of molybdenum fertilizer are the best method of assuring adequate distribution. (Mineral Deficiencies and Toxicities)


MUNG BEAN YELLOW MOSAIC VIRUS (MBYMV)

‘‘‘Mung Bean Yellow Mosaic Virus (MBYMV) ‘‘‘ The initial symptom in systemically infected soybean leaves is vein yellowing along veinlets and severe yellow mosaic can develop on older infections. (Virus Disease)


MYCOLEPTODISCUS TERRESTRIS

‘‘‘Mycoleptodiscus terrestris</b></S></CF> Mycoleptodiscus terrestris causes a crown and root rot of soybeans which are difficult to characterize, because the pathogen is usually associated with other root rot fungi in the field. This disease causes a postemergence damping-off of soybean seedlings which develops as a reddish brown to black cortical decay of crown and root tissues. It can also causes a dark decay of the lateral root system and taproot of older plants.


NEMATODE DISEASES

‘‘‘Nematode Diseases: ‘‘‘ Stunting or suppressed growth, wilting, root lesions or dark discolored areas in roots, root swelling, injured or devitalized root tips, reduced and discolored root systems, and yield reductions are all symptoms of nematode diseases. (Nematode Disease)


NEOCOSMOSPORA VASINFECTA

‘‘‘Neocosmospora vasinfecta</b></S></CF> Neocosmospora vasinfecta causes a dark discoloration of soybean stems and pith, with occasional chlorosis and defoliation of the lower leaves.


NITROGEN DEFICIENCY

‘‘‘Nitrogen Deficiency ‘‘‘ Soybeans are legumes and can fix most or all of their nitrogen requirement if appropriate strains of Rhizobium are present in adequate populations under good conditions. However, soybeans may respond to low rates of fertilizer nitrogen in high-yielding environments. Poor aeration, acid soil pH, high levels of nitrate nitrogen, cold soil temperatures, restricted root growth, or poor inoculation can inhibit nitrogen fixation and improve response to fertilizer nitrogen. Nitrogen-deficient plants become pale green and as the problem persists the leaves turn distinctly and uniformly yellow. Symptoms appear first on the basal leaves and quickly spread to the upper parts. The plants eventually defoliate and are often stunted and spindly. The deficiency can be diagnosed by analyzing leaves for nitrogen, and uprooting the plant to check for nodule formation. Deficiency is best prevented by maintaining an environment conducive to healthy root and nodule development. Inoculation with appropriate strains of Rhizobium may be beneficial if soybeans have not been grown in the field for several years. Liming acid soils generally increases nitrogen fixation. (Mineral Deficiencies and Toxicities)


OZONE

‘‘‘Ozone: ‘‘‘ The only foliar symptoms are an increased rate of yellowing and drying, and abscission, which are virtually indistinguishable from symptoms of normal senescence. (Air Pollutants)


PEANUT MOTTLE VIRUS (PMV)

‘‘‘Peanut Mottle Virus (PMV) ‘‘‘ The first symptoms of peanut mottle are small, enlarging, yellow areas. Dark green islands are produced on young leaves. Later, yellow patches, line patterns, or ring patterns may occur on the third and fourth leaves formed after infection and a mosaic pattern is produced on older leaves. Leaves of infected plants may pucker and curl down at the edges. The best forms of control include isolation from peanut mottle and the use of resistant cultivars. (Virus Disease)


PEANUT STRIPE VIRUS (PSV)

‘‘‘Peanut Stripe Virus (PSV) </b></S></CF> Plants infected with PSTV may develop a mild systemic mottle, a systemic mosaic, chlorotic lesions, or necrotic lesions. PSTV is a potyvirus with flexuous-rod particles about 750 nm long. PSTV is serologically related to blackeye cowpea mosaic virus, clover yellow vein virus, and soybean mosaic virus. PSTV infects numerous legumes, such as soybeans, peanut, blue and white lupines, and clovers (crimson, subterranean, and arrowleaf). The virus is seed-transmitted in peanut but not soybeans.


PHOMOPSIS SEED DECAY (PHOMOPSIS LONGICOLLA)

‘‘‘Phomopsis Seed Decay (Phomopsis longicolla) ‘‘‘ Severely infected seeds are shriveled, elongated, and cracked and appear white and chalky. They usually do not germinate or are delayed in germination. Seeds may also be infected and not show symptoms. Seed infection causes pre- and postemergence damping-off, and under severe conditions stands can be reduced to the point of reducing yields. (Seedborne Fungi and Fungal Disease)


PHOSPHORUS DEFICIENCY

‘‘‘Phosphorus Deficiency: ‘‘‘ Phosphorus deficiency is most commonly observed on soils with insufficient phosphorus. Very acid and alkaline soils are most conducive to deficiency. Phosphorus deficiency may also be induced by cold soil temperatures and soils which are too wet or too dry. Root growth restrictions caused by compaction, insect damage, root pruning by cultivation, herbicide injury, and positional unavailability may cause phosphorus deficiency. Symptoms of phosphorus deficiency are not well defined. The chief symptom is stunted growth and affected plants are spindly and have small leaflets. Leaves turn dark green or bluish green and the leaf blade may curl up and appear pointed. The dark green of the leaves gives the impression that the plants are quite healthy.Flowering and maturity are delayed. Phosphorus deficiency promotes flower abortions and results in reduced pod numbers and low seed yields. Where low soil test indicates phosphorus deficiency, band application of phosphorus fertilizer is more effective. (Mineral Deficiencies and Toxicities)


PHYLLOSTICTA LEAF SPOT (PHYLLOSTICTA SOJICOLA)

‘‘‘Phyllosticta Leaf Spot (Phyllosticta sojicola) ‘‘‘ Lesions form primarily on leaves. Leaf spots are round to oval, irregular, or V-shaped. The spots, at first pale green, become dull gray to tan, with a narrow, dark brown or purplish border. The best forms of control include planting seeds that are relatively free of the pathogen, rotating soybeans with other crops, and plowing under crop residues. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


PHYTOPHTHORA ROT (PHYTOPHTHORA MEGASPERMA)

‘‘‘Phytophthora Rot (Phytophthora megasperma) ‘‘‘ Symptoms on older seedlings depend on the relative susceptibility or tolerance of the cultivar. In low-tolerant cultivars at the primary leaf stage, affected stems may appear water-soaked, leaves may turn yellow and wilt, and affected seedlings may die. On the other hand, in high-tolerant cultivars, the damage may be restricted to roots, and seedlings appear only stunted. Symptoms consist of yellowing between veins and along margins of lower leaves. Upper leaves become yellow, and then the plant wilts completely. The use of resistant cultivars is the best form of control. (Fungal Disease of Roots and Lower Stems)


POD AND STEM BLIGHT AND PHOMOPSIS SEED DECAY (DIAPORTHE PHASEOLORUM)

‘‘‘Pod and Stem Blight and Phomopsis Seed Decay (Diaporthe phaseolorum) ‘‘‘ It has not been established that pod and stem blight stunts plants or reduces the number of seeds. The main losses are from the pod blight phase, resulting in moldy seeds, which may not be harvested, weigh less, or lead to grade reduction. Heavily infected seeds are badly cracked and shriveled and are frequently covered with white mycelium. Lightly infected seeds are often normal in size and appearance. Severely infected seeds often do not germinate. Using resistant cultivars as well as a foliar fungicide are the best two forms of control. (Fungal Disease of Roots and Lower Stems)


POTASSIUM DEFICIENCY

‘‘‘Potassium Deficiency ‘‘‘ Potassium deficiency is most common in soils of low potassium content but may be induced by very wet or dry soils, compaction, and nutrient stratification by tillage. Soils most commonly low in potassium are sandy soils, organic soils, and highly weathered soils. Removal of forage crops containing large amounts of potassium may produce deficiencies in the following crop. Potassium deficiency symptoms are well defined. In early stages of growth, an irregular yellow spotting appears around leaflet margins. The yellow areas group together to form a more or less continuous, irregular yellow border. This symptom is often followed by drying of yellowed areas and downward cupping of leaf margins. Severe deficiency results in deformed and discolored seeds. Deficiencies are best prevented by application of potassium chloride or potassium sulfate according to soil test. (Mineral Deficiencies and Toxicities)


POWDERY MILDEW (MICROSPHAERA DIFFUSA)

‘‘‘Powdery Mildew (Micropshaera diffusa) ‘‘‘ White, powder-like patches form on cotyledons, stems, pods, and leaf surfaces and merge to cover all aboveground plant parts. The best forms of control include using resistant cultivars and foliar fungicides. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


PURPLE SEED STAIN (CERCOSPORA KIKUCHII)

‘‘‘Purple Seed Stain (Cercospora kikuchii) ‘‘‘ The disease is most conspicuous and easily distinguished on seeds. Seed discoloration varies from pink or pale purple to dark purple, and the discolored areas range from specks to large, irregular blotches, which may cover the entire surface of the seed coat. Heavily infected seeds can produce diseased seedlings and reduced resistance. Infected cotyledons often shrivel, turn dark purple, and fall prematurely. Cotyledon infection may spread to the stem, producing dry areas that girdle the stem and kill the young plant. The best form of control is to use resistant cultivars and a fungicide. (Seedborne Fungi and Fungal Disease)


PYTHIUM ROT (PYTHIUM SPP)

‘‘‘Pythium Rot (Pythium spp.) ‘‘‘ Freshly invaded stem tissues are translucent and older lesions become brown producing a watery soft rot. Later, if dry weather sets in, the plants appear dry and shredded. Cortical tissues in the larger roots may disintegrate and slough off, exposing the central woody cylinder. Smaller roots may decay or break away when plants are pulled from the soil. Using resistant cultivars is the best way of controlling the disease. (Fungal Disease of Roots and Lower Stems)


RED CROWN ROT (CALONECTRIA CROTALARIAE)

‘‘‘Red Crown Rot (Calonectria crotalariae) ‘‘‘ Symptoms usually appear in the early pod stage with yellowing of the tops of individual plants. Later, interveinal tissues of may leaves turn light brown. Wilting and defoliation may occur. Infected plants are scattered or confined to restricted areas in affected fields. Use resistant cultivars when available. (Fungal Disease of Roots and Lower Stems)


RED LEAF BLOTCH (DACTULIOCHAETA GLYCINES)

‘‘‘Red Leaf Blotch (Dactuliochaeta glycines) ‘‘‘ The red leaf blotch fungus causes lesions on foliage, petioles, pods, and stems and the lesions are often associated with primary leaf veins. They may initially occur on unifoliolate leaves and are dark red to brown, circular to angular. No commercial procedures are recommended for the control of red leaf blotch. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


RENIFORM NEMATODE (ROTYLENCHULUS RENIFORMIS)

‘‘‘Reniform Nematode (Rotylenchulus reniformis) ‘‘‘ Symptoms of reniform nematode infection include yellowing, stunting, and unthrifty growth, with the production of a large number of empty pods. Galls are not produced on roots, but the root system is severely stunted and may dry out. The most common sign of the nematode is the soil-covered egg masses on roots. Resistant cultivars for reniform nematode exist. (Nematode Disease)


RHIZOCTONIA AERIAL BLIGHT (RHIZOCTONIA SOLANI)

‘‘‘Rhizoctonia Aerial Blight (Rhizoctonia solani) ‘‘‘ Infected leaves are water-soaked and soon take on a greenish brown to reddish brown appearance, finally becoming tan, brown, or black. Lesions may be small spots, or the whole leaf may be blighted. Apply foliar fungicides and use resistant cultivars as control measures. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


RHIZOCTONIA DISEASES (RHIZOCTONIA SOLANI)

‘‘‘Rhizoctonia Diseases (Rhizoctonia solani) ‘‘‘ The sprouted seed is killed and decayed by the causal fungus. Damping-off can occur a few days after emergence. Young lesions are brown, or reddish, depending on the isolate and soil conditions. Use fungicide seed protectants, maintain good soil drainage, and use less susceptible cultivars. (Fungal Disease of Roots and Lower Stems)


ROOT-KNOT NEMATODES (MELOIDOGYNE SPP)

‘‘‘Root-Knot Nematodes (Meloidogyne spp.) ‘‘‘ The primary symptom for identifying the disease is the presence of galls on infected roots. These are produced by the increased size and number of cells in infected and adjacent tissues in response to root-knot nematode feeding. The galls vary in number and size, depending on the intensity of the infection and the nematode species involved. Numerous galls tend to group together so that entire roots may be greatly swollen. Secondary symptoms of the disease are produced, including varying degrees of yellowing and stunting and a tendency of infected plants to wilt in the heat of the day. Using resistant cultivars as well as good cultural practices can help prevent the disease. (Nematode Disease)


RUST (PHAKOPSORA PACHYRHIZI)

‘‘‘Rust (Phakopsora pachyrhizi) ‘‘‘ The most common symptom is tan to dark brown or reddish brown lesions with one to many erumpent, globose, ostiolate uredia. The disease begins with small, water-soaked lesions, which gradually increase in size, turning from gray to tan or brown. Lesions can appear on petioles, pods, and stems but are most abundant on leaves. Lesion coloration, gray-green to dark brown, is dependent on lesion age and the interaction between the soybean genotype and the race of the pathogen. In addition to cultivar resistance, the application of fungicides can reduce rust damage. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


SCAB (SPHACELOMA GLYCINES)

‘‘‘Scab (Sphaceloma glycines) ‘‘‘ Lesions on leaves are frequently visible on both surfaces and are commonly centered on veins. Stem lesions are buff, sometimes with reddish brown margins and young lesions on pods are red to brown. Soybean strains with resistance have been found, but resistant commercial cultivars have not been developed. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


SCLEROTINIA STEM ROT (SCLEROTINIA SCLEROTIORUM)

‘‘‘Sclerotinia Stem Rot (Sclerotinia sclerotiorum) ‘‘‘ Wilting and eventual death of upper leaves are the first symptoms of Sclerotinia stem rot. Leaves become grayish green as drying begins, and they turn brown in time and the leaves remain attached to the stems. Large, black, round to irregularly shaped sclerotia of varying size form on stems, which are partially covered with dense white mycelium. Sclerotia are often formed in the stem pith and are conspicuous only when the stem is opened. Avoid excessive irrigation until flowering has ceased and use resistant cultivars. (Fungal Disease of Roots and Lower Stems)


SCLEROTIUM BLIGHT (SCLEROTIUM ROLFSII)

‘‘‘Sclerotium Blight (Sclerotium rolfsii) ‘‘‘ Light brown lesions, which quickly darken, enlarge until the hypocotyl or stem is girdled. A sudden yellowing or wilting of plants is usually the first symptom. Leaves of infected plants turn brown, dry, and often cling to the dead stem. A leaf spot phase is characterized by circular, tan to brown, zonate lesions with dark brown margins. Alternating soybeans or other susceptible crops with nonhost crops, and planting resistant cultivars combine for good control. (Fungal Disease of Roots and Lower Stems)


SOYBEAN CHLOROTIC MOTTLE VIRUS (SCMV)

‘‘‘Soybean Chlorotic Mottle Virus (SCMV) ‘‘‘ Veinclearing and yellowing followed by spotting are characteristic of the disease. Leaf size is also reduced and infected plants become stunted, with shortened internodes. (Virus Disease)


SOYBEAN CRINKLE LEAF VIRUS (SCLV)

‘‘‘Soybean Crinkle Leaf Virus (SCLV) ‘‘‘ A virus causing crinkle leaf disease was detected in most soybean-growing areas of Thailand. Leaves show crinkling, curling, cupping, and twisting and have veinal enations on the undersurface. (Virus Disease)


SOYBEAN CYST NEMATODE (HETERODERA GLYCINES)

‘‘‘Soybean Cyst Nematode (Heterodera glycines)’‘‘ Foliar symptoms of seedlings vary from slight stunting to severe yellowing and death. Mature plants may be stunted or yellow, or both. The root system has symptoms ranging from slight discoloration to severe drying. Crop rotation is effective in controlling the soybean cyst nematode, because few crops are susceptible. Cultivars with resistance are good when available. (Nematode Disease)


SOYBEAN DWARF VIRUS (SDV)

‘‘‘Soybean Dwarf Virus (SDV) ‘‘‘ Plants infected with the dwarfing strain are severely stunted, turn deep green, become thick and brittle, and are smaller than normal. Plants infected with the yellowing strain are stunted, and a typical interveinal yellowing develops, increasing in severity as the leaves mature and older leaves become thickened and brittle. Insecticides provide satisfactory control of virus spread within a field. Resistant cultivars are recommended where available. (Virus Disease)


SOYBEAN MOSAIC VIRUS (SMV)

‘‘‘Soybean Mosaic Virus (SMV) ‘‘‘ Infected seedlings are spindly, with rugose or crinkled unifoliolate leaves, which may be shaped normally but be spotted or may curl longitudinally downward. A yellowish veinclearing appear along the small, branching veins of young leaves. Leaf margins frequently curve down at the sides. Using resistant cultivars is the most practical form of control. (Virus Disease)


SOYBEAN YELLOW VEIN VIRUS (SYVV)

‘‘‘Soybean Yellow Vein Virus (SYVV) ‘‘‘ Soybean yellow vein virus causing a yellowing of veins on the upper leaves of has been isolated in central Thailand. (Virus Disease)


STEM CANKER (DIAPORTHE PHASEOLORUM)

‘‘‘Stem Canker (Diaporthe phaseolorum) ‘‘‘ The first symptoms occur during the early reproductive stages, with the appearance of small, reddish brown lesions, usually near a leaf node. As the season progresses, the lesions expand longitudinally to form dark brown to black, sunken cankers. Leaf symptoms develop at this stage, with interveinal yellowing and drying characteristic of diseases that restrict water conduction in the plant. The best forms of control include using resistant cultivars and fungicidal sprays. (Fungal Disease of Roots and Lower Stems)


STING NEMATODE (BELONOLAIMUS SPP)

‘‘‘Sting Nematode (Belonolaimus spp.) ‘‘‘ The initial symptoms are small, dark, sunken lesions along the root axis or at root tips. These lesions may enlarge to girdle the roots or extend along the longitudinal axis of affected roots. Terminal growth often ceases, meristematic tissues are destroyed, and roots usually break off at girdling sites so that they have a stubby-root appearance. (Nematode Disease)


SUDDEN DEATH SYNDROME

‘‘‘Sudden Death Syndrome: ‘‘‘ Symptoms first appear on leaves as scattered, interveinal, yellow spots or blotches. The yellow areas may become dry or may enlarge and group together, forming interveinal yellow streaks. These streaks eventually dry out, and only the midvein and major lateral veins remain green. Severely affected leaflets either drop off, leaving the petioles attached, or curl upward and remain attached to the plant. Root symptoms, precede foliar symptoms and are characterized by deterioration of taproots, lateral roots, and nitrogen-fixing nodules. The cortex of affected taproots is a light gray-brown. Control the disease by using resistant cultivars and using good cultural practices.


SULFUR DEFICIENCY

‘‘‘Sulfur Deficiency ‘‘‘ Sulfur deficiency is most commonly associated with low organic matter soils, acid sandy soils, and cold temperatures. The main symptom of sulfur deficiency is small, yellow-green leaves. Stems are thin, hard, and elongated. Leaf symptoms resemble those produced by deficiencies of other elements, such as nitrogen and phosphorus, but stem elongation is characteristic of sulfur deficiency. Many sulfur-containing fertilizers are effective in preventing or correcting sulfur deficiency. Sulfate forms have greatest immediate availability. Elemental sulfur forms have delayed availability because biological oxidation to sulfate is necessary for plant availability. Cold temperatures and large particle size delay this oxidation. (Mineral Deficiencies and Toxicities)


SULFUR DIOXIDE

‘‘‘Sulfur Dioxide: ‘‘‘ Symptoms of sulfur dioxide injury include areas between the leaf veins that are yellow, dry and exhibit irregular cream-colored to light brown dry areas. As with ozone, repeated exposure to sulfur dioxide in low concentrations may accelerate the senescence of leaves. (Air Pollutants)


SUNBURN

‘‘‘Sunburn: ‘‘‘ Minor sunburn appears as small, interveinal, brick red spots on both leaf surfaces. In severe cases, the discoloration spreads over and along the leaf veins. The spots later develop brownish centers, which may crack. Sunburn damage on petioles and stems appears as elongated, brick red lesions, which may be confused with bacterial infections. On pods, brown spots appear, spread, and are often colonized later by saprophytic fungi. (Environmental Stress)


TARGET SPOT (CORYNESPORA CASSIICOLA)

‘‘‘Target Spot (Corynespora cassiicola) ‘‘‘ Leaf lesions are round to irregular and reddish brown and vary from specks to mature spots. Lesions are frequently surrounded by a dull green or yellowish green halo. Infected areas on petioles and stems are dark brown and range from specks to elongated, spindle-shaped lesions. Dark reddish brown circular to oval lesions form on the hypocotyl, taproot, and large lateral roots, sometimes girdling the side roots. The lesions turn dark violet-brown when the fungus sporulates. Most cultivars are tolerant, however, if a problem persists, the best form of control is the use of fungicides. (Fungal Disease of Foliage, Upper Stems, Pods, and Seeds)


THIELAVIOPSIS ROOT ROT (THIELAVIOPSIS BASICOLA)

‘‘‘Thielaviopsis Root Rot (Thielaviopsis basicola) ‘‘‘ A dark brown to black drying of the cortex of hypocotyls, taproots, and fibrous roots forms below the soil line, sometimes resulting in severe root rot. Resistant cultivars is the most effective control against the disease. (Fungal Disease of Roots and Lower Stems)


TOBACCO MOSAIC VIRUS (TMV)

‘‘‘Tobacco Mosaic Virus (TMV) </b></S></CF> The soybean strain (TMV-S) induced veinclearing and mild chlorotic mosaic symptoms. It caused the formation of hexagonal crystals in tobacco leaf trichomes, which are characteristic of various TMV strains. TMV-S is mechanically transmitted but not transmitted through soybean seeds.


TOBACCO RINGSPOT VIRUS (TRV)

‘‘‘Tobacco Ringspot Virus (TRV) ‘‘‘ The most striking symptom is the curving of the terminal bud. Later, other buds on the plant become brown, dry and brittle. Such buds may fall off at the slightest touch. The pith of stems and branches may show a brown discoloration, first near the nodes and then throughout the stem. Brown streaks are occasionally observed on petioles and large leaf veins. Using resistant cultivars is the best form of control. (Virus Disease)


TOBACCO STREAK VIRUS (TSV)

‘‘‘Tobacco Streak Virus (TSV) ‘‘‘ Irregular, yellow spots form later on leaves, followed by systemic symptoms. Infected plants tend to recover and then develop several axillary branches, which are stunted and produce dwarfed leaves. Mosaic symptoms and dry streaks may develop at nodes. Control measures should emphasize protection from introducing infected seeds into soybean fields. In areas where the virus causes significant problems in soybean performance, the production of virus-free seeds for planting should be very useful. (Virus Disease)


WATER STRESS

‘‘‘Water Stress: ‘‘‘ Soybeans die if they are grown in fields that are flooded or submerged for extended periods. Some cultivars are more flood-tolerant than others. Root injury or death results from an exhaustion of the available oxygen in the soil environment. Water stress can also be caused by drought. Throughout the soybean-growing world, this is probably the single most important yield-limiting factor affecting the crop. The symptoms include stunting, poor vigor, and yellowing of the interveinal area of leaves, which changes to a general yellowing with interveinal drying in severe situations. (Environmental Stress)


WILDFIRE (PSEUDOMONAS SYRINGAE TABACI)

‘‘‘Wildfire (Pseudomonas syringae tabaci) ‘‘‘ The wildfire bacterium causes brown, dry spots on leaves. The spots vary in size and shape and are nearly always surrounded by a broad, yellow halo. Use resistant cultivars and follow the control measures suggested for bacterial blight. (Bacterial Disease)


YEAST SPOT (NEMATOSPORA SPOT) (NEMATOSPORA CORYLI)

‘‘‘Yeast Spot (Nematospora Spot) (Nematospora coryli) ‘‘‘ Yeast spot is primarily a disease of soybean seeds, although pods often show small discolored areas where they contact infected seeds. When infection occurs during pod formation, seeds fail to develop and pods drop prematurely. Diseased tissue of young seeds is pale yellow to grayish brown and slightly sunken. The sunken spots are light or cream-colored on more mature seeds. Plant seeds which are relatively free of the pathogen. Control stinkbugs with insecticides. (Seedborne Fungi and Fungal Disease)


YELLOW LEAF SPOT (YLS)

‘‘‘Yellow Leaf Spot (YLS) ‘‘‘ The disease causes rapid defoliation, poor pod fill, and reduced seed size. Lesions develop from pinpoint spots similar to those of bacterial pustule. Later, yellow halos, larger than those of bacterial pustule, develop around the enlarging spots. Young plants may have more spots than older ones, and spots may be reddish brown.


ZINC DEFICIENCY

‘‘‘Zinc Deficiency ‘‘‘ Soybeans are less responsive to zinc than corn, but deficiency may occur in high pH soils of low zinc content. Low soil organic matter, loss of topsoil by erosion or leveling, cold soil temperatures, high phosphorus levels, poor root growth, and compaction can all contribute to deficiencies. Deficient plants have stunted stems and leaves with yellow interveinal areas. Later, entire leaves turn yellow or light green and the lower leaves may turn brown or gray and drop early. Few flowers are formed, and the pods that set are abnormal and slow in maturing. Yield reduction is primarily the result of the reduced number of seeds formed. Mild deficiency may cause yield losses and delayed maturity without visible symptoms. Zinc deficiency is best prevented by soil application of water-soluble zinc fertilizers such as zinc sulfate. Zinc EDTA is also effective, but costs significantly more. Insoluble zinc sources such as zinc oxide in granular form are ineffective. Band applications of 1-5 lbs Zn/acre, such as in a starter application, are most effective. Banding of nitrogen and zinc together improves zinc uptake. Broadcast applications can also be used, but higher rates of 5-10 lbs Zn/acre are normally required for high pH soils. These rates may have residual effects for several years. Foliar application of soluble zinc fertilizers is also effective. A 0.5 to 1% zinc sulfate solution applied with a surfactant in enough water to wet foliage is an effective treatment. Repeated applications at 7-14 day intervals may be necessary. (Mineral Deficiencies and Toxicities)